Final answer:
Dr. Albert's sore legs may be due to the buildup of lactic acid in his muscles, which occurs during intense exercise when glycogen stores are depleted. Lactic acid can cause muscle fatigue and soreness, although other factors also contribute to muscle fatigue.
Step-by-step explanation:
When Dr. Albert woke up with extremely sore legs after his training session, it was likely due to the buildup of lactic acid in his muscles. During intense exercise, the body switches to anaerobic respiration, which produces energy without requiring oxygen. This anaerobic respiration produces lactic acid as a byproduct, which can cause muscle fatigue and soreness.
This buildup of lactic acid occurs when there is exhaustion of energy reserves in the muscle cells. As the body's glycogen stores are depleted, glycolysis becomes the primary source of ATP production, leading to the buildup of lactic acid. This can make the muscles feel tired and sore.
It's important to note that although lactic acid was once thought to be the sole cause of muscle soreness, the actual process of muscle fatigue is more complex and involves other factors such as energy availability, oxygen delivery, and psychological factors.